Storing, transporting and delivering refrigerated goods requires the use of a room or vehicle equipped with a refrigeration or freezer unit or other means of cooling the air within the room or vehicle sufficiently to protect the cargo. One of the most obvious examples of such cargo is refrigerated or frozen foods or medical supplies which, if allowed to warm or thaw, are no longer useable or saleable.
If a vehicle is fully loaded at a single loading site and transported to an unloading site where it is fully unloaded, problems with respect to maintaining a sufficiently cool temperature are not necessarily encountered. However, when a vehicle is not fully loaded and/or is loaded at multiple loading sites and/or unloaded at multiple unloading sites, the risk of loss of refrigeration or increased expense for maintaining a proper refrigeration temperature increases. As delivery proceeds, the vehicle becomes partially emptied. This means that the refrigeration unit then cools not only the remaining cargo, but the empty portion of the vehicle. Each time the vehicle doors are opened and cargo is removed, cool air is lost and the warmer air that replaces it must then be cooled in order to protect the remaining cargo. As a consequence, cargo that is loaded first is also the cargo that is unloaded last and is thus subjected to the full effect of the warming and cooling cycles caused by repeatedly opening and closing the vehicle doors.
One approach to maintaining the cooling capacity of a refrigerated vehicle has been to provide a movable bulkhead that can be repositioned along the vehicle's length. The bulkhead is used to close off that portion of the vehicle that still contains refrigerated goods. However, rigid bulkheads are expensive, complex, difficult to position, heavy, and must be moved each time the goods contained behind them are loaded or unloaded. While some such bulkheads have doors that can be opened, a majority of bulkheads are solid and it is impossible to see precisely what is behind them without first moving them. Further, known bulkheads in the art feature heavy mounting hardware, and are hinged such that the entire bulkhead is lifted and then positioned along the roof of the vehicle when not in use. Such doors are difficult to repair and represent a potential safety hazard should the door hardware fail.
Strip curtains that span the width of a vehicle make it possible for a person to walk through the curtain without having to move it to one side and facilitate the on-loading and off-loading of cargo. However, where goods must be loaded in bulk, such as by forklift truck, it becomes extremely desirable to provide a way for the curtain to be moved from its position stretching across the load space to enable free access to the cargo or the cargo space. Without an easily operated structure to enable the movement of such a curtain along the vehicle length and across the vehicle width there is a tendency for the operator to use the strip curtain improperly.
Another approach to providing temperature control is a curtain or door, fashioned either from overlapping vinyl strips or insulating “blankets” consisting of fabric sandwiched around an insulating core. The strips or blankets are secured along a horizontally extending overhead member. Vinyl strips are made of lightweight translucent or transparent vinyl material, allowing the cargo behind the strips to be seen, while avoiding the storage and manipulation problems inherent in the use of heavy, rigid bulkheads. Such strip curtains have been modified for use in vehicles by providing a horizontally extending aluminum support member from which the individual strips are suspended, and a track-and-trolley extending along the upper walls of the vehicle proximate the roof, whereby the horizontally extending support member can be positioned at various specific sites along the length of the vehicle (see, for example, U.S. Pat. No. 4,639,031 to Truckenbrodt). However, that patent discloses a locking system that can only engage with a series of holes placed at set intervals along the rail system it employs. In addition, the operator must undo the lock on one end of the system and pivot the system in order to move it to a different position in the vehicle. Such pivoting is difficult and dangerous if the operator is moving the system to the rear of a vehicle, because it requires the operator to leave the vehicle and step onto the ground, a docking board, scissor lift, or fork lift, thereby posing a safety issue. Another type of strip door, such as that manufactured by Kason Industries, is stationary and cannot be moved forward or backward inside a vehicle. Yet another system used in the past involves the permanent installation of a horizontal support member to the vehicle wall at a hinge which allows the strip curtain to be stored along the side wall of the vehicle, but does not allow the curtain to be repositioned along the length of the vehicle.
Accordingly, the need exists for a lightweight, ergonomically designed, low maintenance, and flexible thermally insulating barrier that may be positioned at any point along the length of a vehicle, thereby varying the air space required to be cooled, while at the same time providing structure that enables the barrier to be moved to a loading or storage position along side one of the trailer's side walls.